Apparatus for casting core molds



an 3- w. F. EPPENSTEINERQ I 1,894,983

APPARATUS FOR CASTING CORE MOLDS Filed March 4, 1951 n a o a a n a J a331 Mo Bump/1 ad g 1 o n o a a a a n n a a Patented Jan. 24, 1933 UNITEDSTATES PATENT OFFICE.

WILLIAM F. EPPE'NSTEINER OF RAHWAY, NEW JERSEY, ASSIGNOR TO THE AMERICANMETAL COMPANY, (LIMITED), OF NEW YORK, N. Y., A CORPORATION OF NEW YORKAPPARATUS FOR CASTING CORE MOLDS Application filed March 4,

Such molds are used for casting parallelsided copper cakes or slabs asset forth in Patent No. 1,779,534, dated October 28, 1930. A suitablemold for that purpose is set forth in Patent No. 1,785,941, datedDecember 23, 1930. For casting copper cakes or slabs it is preferable tomake the mold of copper with suitable provision for water-cooling,preferably by providing cored passages in the mold walls as in thelast-named patent. For making such copper molds it is preferable to castthe mold around a core which forms the central casting cavity of themold; but great difficulty has been heretofore encountered in suchcasting by reason of the tendency of the cast copper in contractingaround the core to develop cracks which, if they penetrate the waterpassages which are afterward drilled in the walls of the mold, give riseto leakages such as would make the use of such molds highly perilousbecause of the liability of explosions. This difficulty is corrected bythe present invention, whereby the casting of the mold is formed arounda specially constructed, yielding core which is made of a shell of sheetmetal. This metal shell is filled with some heat-conducting material,preferably comminuted metal, such as copper chips or shavings. Suchfilling supports the shell while yielding sufficiently for the purpose.Such filling material affords numerous air spaces so that the imprisonedair has a cooling effect upon the core. It is important tofurther coolthe core by providing a cooling coil suitably located within it throughwhich water is circulated.

A suitable and preferred embodiment of the invention is shown in theaccompanying drawing, where itis applied for the making of a moldadapted for the casting of flat cakes for rolling down into sheetcopper, according to the method set forth in Patent No. 1,779,534,granted October 28, 1930. The perfected construction of mold for eastingsuch cakes is set forth in Patent No. 1,785,941, dated December 23,1930, and illustrated in Figs. 1, 2 and 3 thereof. For making such moldof copper it is preferable for many reasons to cast it around a corewhich forms the central casting cavity of Serial No. 519,936.

molten copper in cooling and after it has apparently solidified, passesthrough a.plas-' tic condition before finally hardening, in whichcondition it has so little cohesion that it cannot resist the tensilestress due to its contraction around an unyielding core. This diflicultyis corrected by the present invention, wherein the casting of the moldis performed around a specially constructed yielding core, as will bemore particularly described.

In the drawing:

Figure 1 is av horizontal section of the mold ready for pouring.

Fig. 2 is a transverse vertical mid-section thereof;

Fig. 3 is a longitudinal mid-section.

Fig. 4 is a perspective view of the sheet metal core.

Fig. 5 is a fragmentary enlargement of a part of Fig. 1 showing adetail.

Fig. 6 is an inverted perspective of a frame for holding the core.

In the drawing, A designates the outer mold in which the future coredmold is to be cast, and B designates the core. C is the bottom of themold A. The mold A is shown as made of opposite side plates (1, a andend plates 6, I). These plates are held together in any suitable manner,preferably by bands or straps surrounding the exterior of the mold andtightened by wedges or otherwise. Such holding means forms no part of myinvention and is known in the art, and may be substituted by any othermeans for fastening the members or sections of the outer mold together.The bottom C may also be fastened in any suitable way, it beingsufficient with a mold of suitable weight to rely on the Weight of themold to hold it in place.

The core is held centered within the mold in anysuitable way, as forexample, by a means which will be later described.

. traction under external pressure.

' The core B, instead of being a solid casting as heretofore, with coredor drilled passages for water circulation, is made as a shell of sheetmetal, as best shown in Fig. 4. The metal used is preferably copper, inthe form of sheet copper or thin plate copper. Its' thickness may vary,but from one-sixteenth to one-eighth inch thickness aflords a suitablerange. The top and bottom of the core are best made. open, the metalsheets or plates 0, 0 being bent to form the sides and ends of the core.The best construction is-to make the core of two sheets or plates flaned up at their sides, these flanged portions at being strongly united bydouble riveting, as

to confine it to the middle portion, as clearly shown in Figs. 1 and 4,leaving bands f, f uncorrugated adjacent the edges of the core. Tofurther preventany bulging or distortion of the core, due to the heatimparted in casting,

it is desirable to connect the opposite sides" at intervals by means ofstays g, g, which may be constructed as copper rods passing across thecore, their ends entering throng holes in the copper sheets and riveteddown thereto, as shown in Fig. 5.

The shell thus constructed is set in place in the mold A and is filledwith some substance which will prevent or limit itsx con- The fillingmaterial has two purposes: .(1) to reinforce the thin shell againstcollapse under the pressure of the metal poureda'round it, at which timeit is weakened by the heat imparted to it, and (2) to provide meansforconducting heat away from the sheet metal shell and thereby protect itagainst being melted out. It also provides interstices within which airon other gas or fl-uidis imprisoned for cooling purposes. The bestresults are obtained with metal, preferably copper, in subdivided form,such as chips,

lamings, shavings, or the like. The filling 1s packed in firmly enoughto afford an adequate support for the core walls.

Cast molds of copper are best made with i a. core ofsheet copper and afilling of comminuted'copper, the core being suitably held ,in itscentral position within the mold. Be-

foreplacing the core, or in any event before ourln the core should becarefully coated with" t e usual bone-ash mixture; and dry. bone-ash.should be sprinkled around the' junction of the core with the baseplate of the mold. After casting, and when the cast copper issufiicientl cooled, the outer mold A is taken apart an removed, and thefilling,

which remains mostly detached, is taken out from the core. The sheetmetal shell then remains, usually partly attached within the coredcavity of the cast mold, and is then to be stripped therefrom, exceptfor some portions,-particularly at the lower corners of the core,whichare found to have become fused to the copper constituting the cast mold.Any such mold requires that its cored cavity be dressed out bymachining, and this operation readily removes an adhering portions orfused-in portions 0 the shell. By making the core and filling of copper,any contamination of the cast metal is avoided. While the fillingordinarily sustains the core against the pressure due to the weight ofthe copper poured around it, yet if the core may yield in places to thispressure, its collapse from that cause is Very sli ht, and the result isreadily corrected in t e course of this machining of the core cavity.

For efiectively cooling the core, it is necessary to provide it with aninternal coolingv means, preferably by circulating water through a coilplaced therein. Such cooling coil is lettered F, and is best introducedfrom above, being suitably held in place within the hollow core andbeing located therein before the filling D is introduced. The coil isbest made of reversed bends, as shown in Fig. 3, and the cross-ties g, gare so located that their presence does not interfere with the insertionof the coil after the hollow shell has been placed in its properlocation within the outer mold. A rapid circulation of waterismaintained through the coil during the v casting; a pressure of from30 to 50 pounds per square inch and a temperature of from to 210 degreesFahrenheit have been found suitable. It is preferable to make the coilof copper pipe, although iron or steel pipe may well be used. 9

With such water-cooled core the method consists in placing the hollowsheet'metal shell (suitably coated with bone-ash, as usual) in the mold,holding it temporarily by any suitable means, such as blocking; thenlowering the coil into place within the shell, fastening the coilfixedly in place by any suitable means (such as will be described), andthen pouring in the. filling material and packing it down thoroughly tofill the spaces around the coil and within the shell as firmly as may benecessary. After removing the blocking, the mold isthen ready forpouring. After the casting has solidified and cooled sufliciently, theouter mold is taken apart and. the coil and filling arerem'oved,-and thesheet metal shell of the core is removed from withm the'cast mold in themanner already described. 4

The core and coil may be variously held in place Within the mold A. Thismay be done by providing means" for holding the shell in place, the coilbeing located by the intervening packing material; or by holding thecoil in place and utilizing the packing material to hold the core inposition. \Vhilc either means may be successfully applied, the latter isconsidered preferable. To hold the shell in its proper location, a.frame G (shown separately in Fig. 6) is slipped over its upper end, asshown in Figs. 2 and 3, and is itself suitably located with respect tothe mold A; this being conveniently done by providing the frame G withpins or dowels j which enter into sockets k in the top of the end plates6, b. The bottom of the shell may be temporarily blocked in place, orthe bone-ash sprinkled around it may afford a sufficient hold, therebeing no strains tending to displace it at the bottom. The coil F isthen lowered into place within the .shell and the filling material isintroduced, being tamped down around the coil, while holding the bottomportion of the coil centrally within the shell. The filling thusintroduced serves to keep the coil and shell properly spaced relativelyto one another. During this operation the coil is temporarily held inplace, as by placing wooden blocks m, m under its horizontal pipes Z, Z,as shown in Figs. 2 and 3. After introducing all of the fillingmaterial, these blocks are no longer needed and may be removed, as wellas any blocking that may have been introduced around the bottom of theshell. The mold is then ready for pouring, as already described.

The improved yielding or slightly collapsible core provided bythepresent invention has certain important advantages over a rigid core.With a rigid or solid core, whether water-cooled or not, the core cannot yield to the contraction of the surrounding cast metal, which givesrise to the liability that the cast metal in cooling may crack by reasonof the internal strains developed within it. The collapsible core mayyield inwardly under the compression exerted against it by the castmetal in cooling. While for this purpose it is preferable to make thecore of corrugated metal, successful results may be attained with ashell of uncorrugated metal. While perfect castings may be made by theuse of such a core Without any other cooling than that afiorded by thepresence of the filling material, yet it is preferable to watercool thecore by applying a circulating coil Within it, of which the constructionshown af- 'fords the best example.

The construction herein shown and described is believed to be the bestway of carrying the invention into practice, but it is to be understoodthat it is susceptible of considerable modification within the scope ofthe appended claims, since the construction and mode of operation may bevaried according to the shape and dimensions of the mold to be cast, andparticularly of its cavity which the core is to form. The presentinvention is applicable to the casting of molds of the shape shown, aswell as other shapes. It is applicable to molds for casting cylindricalbillets, such as are illustrated in Patent No. 1,77 6,355, grantedSeptember 23, 1930. The particular construction and dimensions of theelements of the core and of the means for holding the parts duringcasting may be varied according to the skill or judgment of themetallurgist or casting expert as required by the particular work to bedone.

While the present invention has been designed for the casting of coredmolds of copper, for which purpose the core shell is best made ofcopper, yet it is believed that the invention is applicable for thecasting of molds of other metals, and particularly of metals havingmelting points not materially higher than copper, and when such othermetals are used it may be found preferable to make the core shell of thesame metal as that to be cast, although for metals having not too high amelting point the use of copper for the core shell is preferable forobvious reasons.

What I claim is:

1. An apparatus for making a cast mold having a parallel casting cavity,comprising an outer mold having a cavity conforming to the exterior ofthe mold to be cast, a core of the shape of the object to be cast insuch mold, such core comprising a shell of sheet metal with aheat-conducting filling material of comminuted metal within it, and acooling coil within the core embedded'in such filling material.

2. Apparatus according to claim 1, the core comprising a shell of sheetmetal having corrugations.

3. Apparatus according to claim 1, the core of sheet metal havingopposite flat sides and transverse stays connecting said sides toprevent bulging of the core when packed with the filling material.

4. Apparatus according to claim 1 for the casting of a copper mold, thesheet metal core being of copper and the filling material within it ofcomminuted copper, whereby in case of fushion of the core and filling tothe casting the latter is not contaminated.

In witness whereof, I have hereunto signed my name.

WILLIAM F. EPPENSTEINER.

CERTIFICATE or CORRECTIQN.

Patent No. 1,894,983. v January 24,1933.

I WILLIAM F. EPPENSTEINERt It is hereby certified that error appears inthe printed specification of the above numbered patentrequiringcorrection as follows: Page 1, before line 1,

insert the following paragraph: "This invention relates to apparatus forcasting a metal molds having a cored cavity. and that the said LettersPatent should be read with this correction therein that the same mayconfonn to the record of the case in the Patent Office.

Signed and sealed this 14th day of March, A. D. 1933.

' n 1. Moore;

(Seal) 0 Acting Commissioner of Patents.

